Fluid-pressure brake.



J. W. CLOUD.

FLUID PRESSURE BRAKE.

APPLICATION FILED JULY 18, 1911.

1,076,664.. Patented Oct. 28, 1913.

ITNESSES INVENTbR W%M yaaaw COLUMBIA PLANOGRAPH CO..\VASHINHTON. D. c.

T; Pfhl EMT r sen,

JOHN W. CLQ'UIJ, OF LUNDON, ENGLAND, .ASSIGNOR TO THE WESTINGHOUSE AIIEtBRAKE COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

FLUID-PRESSURE BRAKE.

Specification of Letters Patent.

Application filed July 18, 1911.

orc es.

Patented (lot, 28, 1913. Serial No. 639,115.

To all whom it may concern Be it known that I, dorm W. CLOUD, a citizenof the United States, and a resident of London, England, have invented acertain new and useful Improvement in Fluid- Pressure Brakes, of whichthe following is a specification.

This invention relates to fluid pressure brakes, and more particularlyto an apparatus adapted for the measurement of the volume of the trainpipe of a fluid pressure braking apparatus for the purpose of indicatingto the engineer the approximate length of such train pipe which isproperly coupled and freely open so as to be available for effecting theusual braking operations.

The volume indicator of the present invcntion operates in accordancewith the following general principle: If fluid under pressure bepermitted to escape from a re ceptable which is maintained at a pressuredifferent from that of the atmosphere until a predetermined change inthe pressure in the receptacle is effected, the pressure of the volumeof fluid thus transferred from the receptacle, provided said volume isfixed, will be a measure of the volume of the receptacle practicallyregardless of the initial pressure therein.

lit has previously be proposed to utilize the above principle formeasuring the volumetric capacity of the train pipe of a fluid pressurebraking apparatus by providing an automatic valve arranged to permit thepassage of fluid under pressure from or into the train pipe until apredetermined change in the pressure therein has occurred, the fluidpassing through the said valve during this operation being estimated bya measuring chamber or other suitable device. In one such apparatus thevalve is arranged to be operated by a diaphragm, one side of which issubject to fluid at the initial pressure of the train pipe, and theother side of the dia r phragm being in open communication with thetrain pipe, and the fluid under pressure bein allowed to enter or escapethrough the valve. As soon as a predetermined change of pressure in thetrain pipe has occurred the diaphragm is arranged to be operated bymeans of a spring so as to close the valve and thereby cut offcommunication between the train pipe and the atmosphere, the amount offluid under pressure which has passed through the valve being measuredin any convenient way. It has been found 111 practice that with thisarrangement the closing of the valve when the desired change of pressurein the train pipe has occurred is not sufiiciently effective ordetermmate, since as soon as the train pipe pressure has alteredsutliciently to permit the closure of the valve, 110 further change inthe train pipe pressure occurs and the pressure tending to keep thevalve closed is thus extremely small, with the result that gradualleakage through the valve may take place, thus interfering with theaccuracy of the measurement.

The present invention has for its object to provide an improved valvemechanism for effecting a positive and definite closure of the trainpipe as soon as the desired change in pressure in the latter has takenplace and comprises essentially a valve (preferably a slide valve) theoperation of which is controlled by means of an auxiliary valve operatedby a diaphragm subject on one side to the initial pressure in the trainpipe and on the other side to the gradually varying pressure in thelatter, as fluid is with drawn therefrom during the measuring operation.

In the accompanying drawing, Figure 1 is a sectional view on the lineC-G of Fig. 3 of a preferred form of valve mechanism constructed inaccordance with my invention and showing the parts in normal position,the passages 18, 14:, 20, 21, and 26 therein, While shown in dottedlines, being in front of the plane of section and the slide valve tbeing sectioned on the line (Z--(Z of Fig. 5; Fig. 2 a sectional view ofthe valve mechanism on the same plane as Fig. 1, showing the parts inposition for measuring the volume of the train pipe; Fig. 3 a section onthe line ca -a of Fig. 1, looking in the direction of the arrow; Fig. 4a sectional view of the valve mechanism, taken substantially on the lineb-b of Fig. 1 and looking in the direction of the arrow; and 5 a faceview of the main slide valve and a plan view of the valve seat therefor.

Referring now to the figures of the drawing, the valve mechanismcomprises a loose- 1y fitting piston 1 located in the chamber 2 andsubject on one side to the pressure of a light spring 3 and controllingthe movement of a slide valve 4 in a valve chamber 5. The valve chamber5 is permanently connected to the train pipe 31 through passages 6 and 7leading thereto.

In the valve casing, a controlling chamber 8 is provided, which isseparated from the passage 7 leading to the train pipe by means or adiaphragm 9 adapted to control the operation of an auxiliary valve 10which is normally held in its open position by means of a spring 11. Thediaphragm 9 is provided with the usual guide stem 9 slidably mounted inthe usual guide bearing 9. The valve 10 controls communication from aspace 12 connected by means of a passage 13 with the piston chamber 2,to a passage 1 1 terminating in a port- 15 in the seat of the slidevalve l, said valve being provided \Vlbh a cavity 16 adapted to connectthe port 15 with the passage 17 when the slide valve is in its operativeposition.

it manually controlled plug cock 18 is provided which is capa 20 ole ofbeing set in one or other of two positions by means of a handle 19. Thecook 18 is formed with a number of passages in its body portion, apassage 20 in the cock serving in one position of the handle to connectthe valve chamber 5 with the controlling chamber 8 by means of passages21, as shown in Fig. 3. In the same position of the handle 19 a passage22 in the cook 18 serves to connect a passage leading to a measuringchamber 32, with the atmosphere through an exhaust port 24. The passage20 is also adapted, when the handle 19 is operated, to establishcommunication from a passage 26 in the valve casing leading to thepassage 13 to an exhaust passage 25, a cavity 28 and a passage 29 in thecock being arranged in the measuring position of the handle 19 toestablish communication from a passage 30, leading to the underside ofthe slide valve i, to the passage 23 leading to the measuring chamberand also from the passage 30 to the passage 17, before referred to, asshown in Fig. 2.

The operation of this form of the apparatus is as follows: When the plugcook 18 is in the normal position, shown in Fig. 1, the measuringchamber 32 is connected to the atmosphere through the passage 23,

the passage 22 in the plug cock, and the exhaust port 2% in the valvecasing, and the controlling chamber 8 is connected through the passages20 and 21 with the valve chamber 5, and as passages 6 and 7 connectvalve chamber 5 with the train pi e 31, both sides of the diaphragm 9are now exposed to train pipe pressure and the valve 10 is held in itsopen position by the action of the spring 11. When it is desired toeltect a measurement cat the volume or" the train pipe, the plug cock 18is moved by means of the handle 19 from the position shown in Fig. 1 tothe position indicated in Fig. 2 6-5 of the drawing, and during thismovement the passage 20 in plug cook 18 registers with the passage 26,leading to the passage 13 and exhaust passage 25, so that a smallquantity of fluid under pressure passes from the chamber 2 to theatmosphere through the exhaust passage 25. The chamber 2 being thusmomentarily connected to atmosphere, the fluid under pressure on theopposite side of the piston 1 moves the piston and slide valve 4 intosuch a position that the passage 30 leading to the underside of theslide valve is uncovered. The movement of the plug cock from its normalposition cuts off communication from the chamber 5 to the controllingchamber 8 so that the latter is entirely isolated and contains fluid theinitial train pipe pressure. The plug cock having reached its measuringposition, communication from the measuring chamber 32 to the exhaustoutlet 12% is cut off and communication is established from the valvechamber 5, through passage 30, passages 22 and 29 in the plug cock topassage 23 and the measuring chamber 32. Fluid under pressure from thetrain pipe thereupon flows into the measuring chamber by way of thepassages (i and 7, valve chamber 5, and the passage 30, and the flow offluid from the train pipe continues until the train pipe pressure on theright hand side of the diaphragm 9 is sufiiciently less than thepressure in the controlling chamber 8 to permit the diaphragm 9 to movetoward the right and close the valve 10 against the action of thespring. It will be noted that so long as the valve 10 is open, the fluidleaking past the loosely fitting piston 1 into the chamber 2 isconducted into the measuring chamber through the passage 13, past thevalve 10, through passage 1%, the cavity 16, passage 17 and cavity 28 inthe plug cock, so that the piston 1 is maintained in its extreme righthand position, against the action of the spring 3, by the pressure inthe valve chamber 5. As soon as the valve 10 is closed the escape offluid from the chamber 2 to the measuring chamber is prevented and thepiston 1 moves back to its original position by equalization of pressurepast the piston, and under the action of the spring 3, so as to closethe passage 30 and cut oil the flow of fluid under pressure from thetrain pipe. The controlling spring 11 is adjustable so that the flow offluid under pressure from the train pipe is stopped as soon as apredetermined reduction in pressure therein has occurred, for example,say five pounds per square inch, and the pressure of fluid which hasen'- tered the measuring chamber is indicated in any suitable way,thereby affording a measurement of the voliune of the, train pipe. Theinitial movement of the slide valve 4t back to its original position, assoon as the valve 10 closes, causes the passages I l and 17 to bedisconnected so that the leakage of fluid from the chamber 2 is entirelyprevented, thus efi'ectually insuring the complete return of the pistonunder the action of the spring 8. It is es scntial that during themeasuring operation the controlling chamber be absolutely hermeticallysealed by the plug cock 18 since a small leakage from this chamber Willvery seriously affect the accuracy of the measurement, and it istherefore desirable that a pressure gage be provided for the train pipeso as to indicate independently that the predetermined reduction ofpressure has been effected. .ln carrying out the measurement, it is ofcourse necessary that the train pipe should be cut oil as far as it ispossible from any external source of pressure and for this purpose it isdesirable to close the feed grooves to the auxiliary reservoir of thebrake system by effecting a small reduction in the train pipe pressurebefore moving the plug cock to the measuring position as is usual forthe purpose of testing the brakes. After having eiiected a reduction ofthe train pipe pressure for this purpose a short interval of time shouldbe allowed to elapse before moving the plug cock to its measuringposition, in order to allow an surges of air in the train pipe tocompletely subside so that the pressure in the controlling chamber canbecome entircly equalized With the uniform pressure in. the train pipebefore proceeding With the measurement.

The construction of the various elements of which the improved valvemechanism is composed is immaterial and various modifications in thisrespect may be made Without departing from the spirit and scope oi theinvention.

Having now described my invention, What it claim as new and desire tosecure by Lettors Patent, is:

l. in a fluid pressure brake, the combination With a train pipe, of areceptacle, means for establishing communication from the train pipe tothe receptacle, an automatic valve mechanism for controllingcommunication from the train pipe to said receptacle, a chamber, meansfor isolating the chamber from communication With the train pipe, and avalve device subject to the oppoi-iing pressures of the train pipe andsaid chamber whereby the decrease of pressure on one side of said valvedevice will close com munication from the train pipe to said receptacle.

2. In a fluid pressure brake, the combination with a train pipe, of areceptacle, a valve mechanism for controlling communication from thetrain pipe to said receptacle, manually operated means for varying thepressure on one side of said valve mech anism for operating same to opencommunication for venting air from the train pipe to said receptacle, achamber, communication from the train pipe to said chamber being closedby said manually operated means, and a valve device subject to theopposing pressures of said chamber and the train pipe for alsocontrolling the pressure on said valve mechanism for operating same toclose said communication to said receptacle.

In a fluid pressure brake, the combination with a train pipe, of areceptacle, a valve for controlling communication from the train pipe tosaid receptacle, a cylinder, a piston therein for operating said valve,manually operated means for venting fluid from one side of said pistonto actuate the same to open communication from the train pipe to saidreceptacle, a chamber, communication from the train pipe to said chamberbeing closed by said manually operated means, and a valve device subjectto the opposing pressures of the train pipe and said chamber forcontrolling the release of fluid from said piston to effect the movementof said piston and valve to close said communication to said receptacle.

l. In a fluid pressure brake, the combination with a train pipe, of areceptacle, a chamber, a valve for controlling communication from thetrain pipe to said receptacle, a cylinder, a piston therein foroperating said valve, manually operated means for closing communicationfrom the train pipe to the chamber and for venting air from one side ofsaid piston to actuate the same, a valve for stopping the venting offluid from such side of said. piston, and a movable abutment subject tothe opposing pressures of the train pipe and said chamber for operatingsaid last named valve.

5. In a fluid pressure brake, the combina tion With a train pipe, of areceptacle, a valve for controlling communication from the train pipe tosaid receptacle, a cylinder, a piston therein for operating said valve,manually operated meals for venting air from one side of said piston toactuate the same, a valve for controlling communication from one side ofsaid piston to said recep tacle, a chamber containing fluid at originaltrain pipe pressure and a movable abutment subject to the opposingpressures of the train pipe and said chamber for closing the lastnan'ied valve upon a predetermined re duction in train pipe pressure.

6. In a fluid pressure brake, the combination vvith a train pipe, of areceptacle, a valve for controlling communication from the train pipe tosaid receptacle, a cylinder, a piston therein for operating said valve,manually operated means for venting air from one side of said piston toactuate the same, a valve for controlling commiiinication from one sideof said piston to said receptacle, a chamber containing fluid atoriginal train pipe pressure and a movable abutment subject in onedirection to train pipe pres sure and the pressure of a spring and inthe opposite direction to the pressure in said chamber for closing saidlast named communication upon a predetermined reduction in train pipepressure.

7. In a fluid pressure brake, the combination with a train pipe, of aclosed receptacle, a main valve mechanism for controlling acommunication from the train pipe to said receptacle, manually operatedmeans for varying the pressure on one side of said valve mechanism tooperate the same to open said communication, an auxiliary valvemechanism and means whereby the same is operated upon a predeterminedreduction in train pipe pressure for varying the pressure on one side ofsaid valve mechanism to thereby operate same to close saidcommunication.

8. In a fluid pressure brake, the combination with a train pipe, of aclosed receptacle adapted to receive fluid vented from the train pipe, amain valve for controlling communication from the train pipe to saidreceptacle, a cylinder, a piston therein normally subject on oppositesides to fluid under pressure for actuating said valve, a diaphragmsubject on pressure, and means whereby the same is subjected on theopposite side to a controllable fixed pressure, there being a passageleading from one side of said piston, an auxiliary valve operated bysaid venting fluid through said passage corresponding with apredetermined reduction in train pipe pressure, and a manually operatedcock having an operating position for connecting the train pipe withsaid closed 40 receptacle, and having means for venting fluid from saidcylinder in the movement of the cock to said operating position.

In testimony whereof I have hereunto set mv hand.

JOHN W. CLOUD.

\Vitnesses A. A. BERGIN, O. P. LnDDoN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

one side to train pipe 30 diaphragm for 35

